Polycarboxylate polymers are well-known ingredients of detergent compositions and provide various benefits. They are used, for example, as antiredeposition and antiincrustation agents, and for supplementary detergency building, especially in conjunction with water-insoluble aluminosilicate builders.
Acrylic and maleic polymers have been especially widely used. For example, GB 1 596 756 (Procter & Gamble) is concerned with maleic polymers, especially methyl vinyl ether/maleic anhydride copolymers, and their use as auxiliary detergent builders in phosphate-built compositions. GB 1 460 893 (Unilever) discloses the use of polyacrylates as antiincrustation agents in detergent compositions containing ortho- and pyrophosphate builders. EP 25 551B (BASF) discloses the use of acrylic/maleic copolymers as antiincrustation agents. EP 124 913B (procter & Gamble) discloses detergent compositions containing a combination of polyacrylate and acrylic/maleic copolymer.
Although various polymers have been disclosed in the literature, only polyacrylates and acrylate/maleate copolymers have found widespread use in commercial detergent products.
The present invention is based on the observation that certain carbon backbone polycarboxylate polymers having hydroxyl and or hydroxymethyl groups in close proximity to the carboxyl groups exhibit efficient improved detergency building (calcium binding).
GB 1 328 749 (Solvay) discloses the use as metal ion sequestrants of water-soluble salts of poly (alpha-hydroxyacrylic acid) of the formula I : ##STR1## wherein the R groups are hydrogen atoms or C.sub.1 -C.sub.3 alkyl groups, and M is an alkali metal or ammonium cation. The salts may be used as replacements for sodium tripolyphosphate as builders in detergent compositions.
2-hydroxymethylacrylate monomer of the formula II: ##STR2## wherein R is a lower alkyl group, is disclosed in EP 184 731A (BASF), and the polymerisation of methyl ester derivatives has been reported by L J Mathias, S. J. Kusefoglu and A. O. Kress, Macromolecules 1987 20 2326. Polymers in free acid or salt form, that is to say, containing units of the formula III: ##STR3## wherein M represents a hydrogen atom or a solubilising cation, are not disclosed.
U.S. Pat. No. 3,743,669 (Hillman & Co/Celanese Corp) discloses the preparation of 2-(1-hydroxymethyl)acrylic esters and their polymerisation to produce adhesives. U.S. Pat. No. 3,066,165 (Rosenthal et al/Koppers Co Inc) discloses the preparation of alkyl .alpha.-(hydroxymethyl) acrylates, and their use as copolymers in latices.